The invention relates to a device and a method for attaching a printing web to a webbing sail and a device and a method for webbing-up a printing machine.
Automatic webbing systems have been incorporated into web-fed printing presses to reduce the time it takes to web a press by hand. Webbing devices or sails that are attached to such systems are used to pull the web through the press. Double-sided tape is typically used to attach a web to the webbing sail. Unfortunately, two types of tape exist, the easily removable and not so easily removable. If the wrong tape is used, it is extremely difficult to remove the web from the sail. After many web-ups, the tape begins to build up on the sail, possibly preventing it from fitting between a blanket-to-blanket nip. In addition, if the web is skewed while it comes in contact with the tape, there is no opportunity to reposition it. If the web and the sail are skewed, a shear force will be applied to the web as it is pulled through the press, causing web breaks.
Spatial constraints restrict the overall thickness of the web and the sail. Together, the combined thickness of the web and the sail must be less than 0.094 inches (2.4 mm) which is the gap between upper and lower blanket cylinders for both Commercial and Newspaper presses produced by Heidelberg Web Systems.
A device used by MAN-Roland attaches a web to a webbing device by using two thin magnetic sheets which sandwich the web therebetween. However, magnetic attraction may be insufficient to provide the required holding force to prevent the web from slipping out. Magnetized material may also facilitate the transfer of small metallic debris from one area of the press to another.
German Published, Non-Prosecuted Patent Application DE 198 37 361 A1 discloses a device for drawing a paper web into a printing machine. The web is provided with a draw-in tip having a wedge-shaped reinforced element coupled to a draw-in device by hook and eye, magnetic or snap fasteners. The web may be fastened to the reinforced element by an adhesive strip or plug-in tongue. In another embodiment, the web is placed over a female element and engaging pieces on a male element pierce the web and enter openings in the female element. The elements are connected to each other mechanically, by a snap closure or by a hook and eye closure.
German Published, Non-Prosecuted Patent Application DE 198 37 362 A1 discloses another device for drawing a paper web into a printing machine. A web is placed between male and female so elements. The male element has shaped elements in the form of triangles, cones, pyramids or cylinders or irregular shapes and the female element has depressions with matching shapes, between which the web is placed. The elements are clamped together magnetically by a snap closure, a spring force or a hook and eye closure. In another embodiment, cylindrical rods in a fan shape are connected to the web by placing hoses over the web and the rods.
The engaging pieces as well as the shaped elements and matching depressions all require external measures which act mechanically with a snap closure, with a hook and eye closure or with spring force to hold them in place on the web. As the webbing sail is pulled and increased tension is placed on the web, those devices tend to loosen around the web and/or tear the web. In addition, the use of such external measures is cumbersome and time-consuming.
It is accordingly an object of the invention to provide a device and a method for attaching a printing web to a webbing sail and a device and a method for webbing-up a printing machine, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of to this general type and which use mechanical measures to quickly and accurately attach, and if necessary reposition, a web to a webbing device without the use of external measures, without the use of a consumable, such as double-sided tape, and while minimizing the danger of loosening and/or tearing the web.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for attaching a printing web to a webbing sail having a trailing edge. The device comprises two thin, flexible sheets to allow wrapping around various rolls. At least one edge of the sheets is connected to the trailing edge of the webbing sail. The sheets are to be sandwiched about the printing web for attaching the printing web to the trailing edge of the webbing sail. Protrusions are obliquely disposed on the sheets, for instance toward a web travel direction, for gripping the printing web with increased force as the webbing sail pulls the printing web with increased tension, thereby tending to draw the two sheets together.
In accordance with another feature of the invention, the protrusions are points, such as corners of triangles, punched into the sheets. The triangles may be stamped through the sheets at an angle relative to the web travel direction.
In accordance with a further feature of the invention, the webbing sail may be formed of PVC material and the sheets may be formed of stainless steel.
In accordance with an added feature of the invention, one of the sheets is directly attached to the webbing sail and a flexible piece connects the other of the sheets to the webbing sail.
In accordance with an additional feature of the invention, the protrusions are staggered on the respective sheets and the sheets have holes formed therein between the protrusions. The protrusions on each of the sheets extend into the holes in the other of the sheets. Layers of a compressible material are each disposed on a respective one of the sheets for receiving ends of the protrusions passing through the holes.
With the objects of the invention in view, there is also provided a method for attaching a printing web to a webbing sail having a trailing edge. The method comprises providing two thin, flexible sheets having protrusions obliquely disposed thereon, for instance toward a web travel direction. At least one edge of the sheets is connected to the trailing edge of the webbing sail. The printing web is sandwiched between the two sheets for attaching the printing web to the trailing edge of the webbing sail. The printing web is gripped by the protrusions with increasing force as the webbing sail pulls the printing web through the printing machine with increasing tension.
With the objects of the invention in view, there is additionally provided a device for webbing-up a printing machine, comprising a thin, flexible webbing sail to be pulled through the printing machine. Two thin, flexible sheets are to be sandwiched about a printing web. At least one edge of the sheets is attached to the trailing edge of the webbing sail. Protrusions are obliquely disposed on the sheets, for instance toward a web travel direction, for gripping the printing web with increased force as the webbing sail pulls the printing web with increased tension.
With the objects of the invention in view, there is furthermore provided a method for webbing-up a printing machine, which comprises providing a webbing sail having a trailing edge. Protrusions are obliquely formed on two thin, flexible sheets, for instance toward a web travel direction and clearance holes aligned with the protrusions are formed in the opposite sheet. At least one edge of the sheets is attached to the trailing edge of the webbing sail. A printing web is sandwiched between the two sheets and the printing web is pulled through the printing machine with the webbing sail while gripping the printing web with the protrusions with increasing force as the webbing sail pulls the printing web through the printing machine with increasing tension.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device and a method for attaching a printing web to a webbing sail and a device and a method for webbing-up a printing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.